1. Field of the Invention
The present invention relates to a box-shaped packing case used to accommodate a video tape cassette or the like.
2. Description of the Related Art
A conventional packing case, for example, a box-shaped packing case used to accommodate a video tape cassette or the like, is designed so that each of both end portions of the packing case 50 in its longitudinal direction (up-and-down direction in FIG. 1) thereof is constructed by an overlap portion. That is, the overlap portion is constructed as follows. First, first and second folding plates 52 and 53 are folded from two directions. The outer shape of each folding plate 52, 53 at the boundary portion therebetween is designed so that they are not overlapped with each other when they are folded (see FIGS. 2 to 4).
As shown in FIG. 1, a third folding plate 54 is folded from another direction so as to be overlaid on the first and second folding plates 52, 53. Liquid paste 56 is coated at a predetermined position shown in FIG. 1 on the first folding plate 52 in advance, and the third folding plate 54 thus folded adheres onto the first folding plate 52 through the liquid paste 56.
In the conventional packing case 50 as described above, however, the boundary portion between the first and second folding plates 52 and 53 when they are folded is formed so as to have a relatively long slant portion D, and thus the edge of one end (right end in FIG. 4) of a liquid-paste 56 coated area (adhesion area) is limited to the position which is far away from the back portion 58 of the packing case 50 by the length L.
Therefore, since no liquid paste 56 is coated beneath a corner portion 54a of the third folding plate 54, the corner portion 54a is floated as shown in FIG. 5 after the third folding plate 54 is adhesively attached onto the first folding plate 52, and if it is more severely floated, it might peel off.
If the end portion of the liquid-paste 56 coated area in its length direction (adhesion length) is forcedly extended to the back portion 58 in order to prevent the peel-off state of the corner portion 54a, that is, the length L from the back portion 58 is forcedly shortened, the end portion of the adhesion area is overlaid on the gap of the slant portion D at the boundary portion between the first and second folding plates 52, 53, so that a part of the liquid paste 56 invades through the gap into the packing container 50.
Therefore, the liquid paste 56 may adhere to the video tape cassette accommodated in the packing case 50, and thus the video tape cassette may adhere to the inside of the packing case 50, so that it cannot be taken out from the packing case 50, or the adhesion of the liquid paste 56 to the video tape cassette deteriorates the quality of the video tape cassette as an article of commerce, or makes a user feel uncomfortable.